A wireless communication system is provided for reducing the probability that latency before data transmission increases when a mobile station that is actually in sync is judged to be out of sync. A base station causes the timing calculation part to calculate the timing advance (TA) of a transmit timing from the mth mobile station; causes the timer adaptive control part to obtain the traveling speed or the time variation in TA of the mth mobile station and, adaptively determines and outputs as the timer update information the length of the mth first timer within an M number in total of synchronization timers and the length of the second timer of the mth mobile station and update the length of the mth first timer; and transmits from the downlink transmission part a downlink signal which contains timer update information.